Loripcs.] PELECYPODA. 913 



The anterior larger, elongated, the posterior shorter. Pallial line 

 distinct, simple. 



Diameter Ant. -post.. 7-5 mm. ; dorso- ventral, 7-2 mm. : thick- 

 ness, 4-2 mm. 



Type, from the Pliocene, in the Canterbury Museum, Christchurch. 



Hab. Off Great Barrier Island, in 110 fathoms ; near Cuvier 

 Island, in 38 fathoms, live specimens (Captain Bollons) ; near Channel 

 Island, in 25 fathoms. 



Fossil in the Miocene and Pliocene. 



Genus 2. DIVARICELLA, von Martens, 1880. 



Divaricella, von Martens, Beitr. z. Meeresfauna von Mauritius und Seychellen, 

 1880, 321. Type : Lucina angulifera, v. Mts. = ornata, Reeve, not of 

 C. B. Adams. Cyclas, Morch, 1853 ; not of Lamarck, 1799. Egraca, 

 Leach, 1852. Strigilla, Turton, 1822. Lucina of many authors. Loripes, 

 Wood, 1840. 



Valves suborbicular, convex, subequilateral, with inconspicuous 

 beaks, no dorsal areas, 2 cardinal teeth in each valve, the laterals 

 variable, the posterior distant, usually obsolete ; the anterior feeble, 

 adjacent. Ligament and resilium set in a groove, but not internal ; 

 the excavated striae forming an angle on a line radial from the beaks. 



Fossil in the Tertiary. It appears first in the Eocene of Australia, 

 and most likely migrated from there to New Zealand. 



I. Divaricella Cumingi, A. Adams and Angas, 1863. Plate 58, 

 fig. 18. 



Lucina (Cyclas) Cumingi, Ad. & Ang., P.Z.S., 1863, 426, pi. 37, f. 20 ; Chall. 

 Rep., xiii, 177. L. divaricala, Lamarck : Gray, Dieff. N.Z., 257 ; Hutton, 

 C.M.M., 74 ; J. de Conch., xxvi, 51 ; M.N.Z.M., 155 ; not of Lamarck. 

 L. dentata, Wood: Hutton, P.L.S. N.S.W., ix, 525; not of Wood. 

 Divaricella Cumingi, Ad. & Ang., Index, 92 ; Hedley, T.N.Z.I., xxxviii, 

 74. 



Shell orbicular, subglobose, rather thin, with divaricate sculpture, 

 nearly equilateral, rather thin, posterior extremity truncate. Beaks 

 contiguous, but slightly raised, directed forward, slightly in front of 

 the centre, concentrically finely striate. Anterior end and basal margin 

 regularly rounded, the posterior end squarely truncate. Lunule long 

 and narrow, tapering anteriorly ; the anterior area below the lunule 

 sharply defined, with irregular concentric strise. Sculpture consisting 

 of rather distant sharp ridges forming an angle on a line from the 

 beaks to the anterior part of the basal margin, the ridges much closer 

 at the angle ; interstices much broader than the ridges, with fine 

 concentric growth-lines. Colour white. Interior white, porcellanous, 

 not shining. Margins smooth, sharp. Hinge : Right valve with a 

 strong triangular cardinal tooth in the centre and a deep pit on either 

 side, a smaller oblique cardinal in front, directed forward ; the anterior 

 lateral is a large tubercle with a deep chink where the adductor-scar 



